Radio broadcast selecting and distributing system



J+S 5 .um 6, 192s. 1,522,361

' E. E. CLEMENT RADIO BROADCAST SELECTING AND DISTRIBUTING SYSTEM N Filed Fep. 29, 1924 i HTW Patented Jan. 6, 1 925.

lUran-:o lSTATES PATENT oFF IC E EDWARD E. CLEMENT, F WASHINGTON, DISTRICT F COLUMBIA, ASSIGNOR T0 ED- WARD F. COLLADAY, F WASHINGTON, DISTRICT OF COLUMBIA.

RADIO BROADCAST SELE'CTING AND DISTRIBUTING SYSTEM.

Application tiled February 2B, 1924. Serial No. 696,076.

ment in the system described and c`laimed.in-

my prior copending application, filed Aul:rust 14, 1922, Serial No. 581,829.

The present invention has for its object to provide improved `centralized means for receiving from primary or distant stations and relaying the same modulations to subscrihers in a local area, or inv other words,

' with simultaneous an imprwement in collecting and regional distribution. I attain my object by employing a superheterodyne receiving circuit, and retransrnitting on the beat wave, for reception in the local area, this in combination supervision, metering, etc., of the service thus rendered, over wired circuits to the subscribers sta- 'tions, all as in the aforesaid prior cepending application. At each subscribers' station I locate a receiving set 'which may be fed with direct current over the subscribers wired line circuit. and said receiving set may be of any desired type. provided the construction and adjustment of all the subscribers sets is standard and uniform, so that they are tuned once for all to the same Wave length, being the beat wave length transmitted from the local central station relay transmitter.

My inventionis illustrated in the accompanying drawing, in which the figure is a diagram showing a central station, a subscribers station and the. line circuit interconnecting them.

leien-ring to the drawing C is a central station containing 'a telephone sivtchl'ioard and a radio switchl'ioard, each with connective apparatus and containing multiple line terminals for the subscribers telephone line ifi- 1 7 which extends to the suhscrihers station A, Where a standard telephone instrument set is connected as shown. Tapped ofi' from the wire 17 is a loop containing the windings of a relay L* shunted by a condenser. This relay'controls the normal concontrol, i

nection of wires 52 and 53 to the eiwires 16-17, and also controls the normal connection of a companion relay Li to the line wlre 16, which is the tip wire of the pair. The relay L in turn controls output terminals of the radio detector set 36,'which are normally retracted so as to connect the' set to the -operators receiving` phone 36, which may be of any desired or suitable type. When the relay Lls is energized, it disconnects .the subscribers phone 3G, and connects hs'jradio set across thc line A16- 17, so that the operator at the radio switchboard can "listen in over the line and ascertain if' the central oiice beat wave 1s 1n tune with and is being properly received by the subscribers instrument 36". The relay L is controlled by the radio switchboard operator by means of the key Kw, connected to the plug circuit Pm. When the plug of this circuit is inserted in the subscribers jack at a', a busy tone test is put on the multiple or test thimble of the line on the telephone switchboard, battery B is connected to thecut-ofi' relay .11', the operators' headset is bridged across the conduetor 16--17, and finally key Km being closed, battery B throws current out on the tip side of the line 16 to energixe relay Ls and enable the operator to listen in on the subscribers radio set. lVhile I have shown the subscribers receiving telephone cut ofi' durin this operation, it may remain connectet the cut-ofi1 being an'additional fea` ture which enables the central ofiiee to deprive the subscriber of all service in case of necessity. When the operator is satisfied, and desires to be disconnected from the line the key Km is opened, and if desired the plug is pulled from the jack at m, thel parts then all assuming thelrinormal position shown in the drawing when receiving may be continued at the subscribers station in the ordinary way. Incoming telephone calls' from the station A and outgoing calls resulting from telephone operators plugging in as at 'ack :1:2 result in eneroizin rela L# s g y which isplaces relay L5 and totally disLv 'connects the, radio detector set 36 from the line 16-17, this condition being maintained as long as the line is in use for conversation.

Radio transmitter T comprises an antenna circuit 1, coupler 2, local oscillator circuit 3, the first detector 4, radio amplifying units 5 and 6, and a radiating circuit 7. Since the essential part of the heterodyning operation is in the elements 1, 2, 31,' 4, it is to be understood that the arrangement of the amplifying and other stages between the first detector 4 and the radiating circuit T are subjectl to modification in accordance with good practice. The beat waves at'ter being sutlicicntly amplified may be directly thrown upon the radiating circuit, or may be communicated through a modulator and oscillator circuit, by which increased energy may be imparted to the radiating beat :trequency waves. Ordinarily such energy may be communicated in sutlieient quantity by the oscillator 3, the tubes 5 and 6 being essentially power tubes and operating on an desired voltage.

lhe important point in the present invention is this: to select ditferent stations vand receive from any distant station at any wave length or frequency, heterodyning by means of the local oscillator 3 with said incoming modulated waves, and by proper tuning` ot' the oscillator circuit 8 always producing a standard beat wave to which the subseriber`s instruments in the local area are permanent ly tuned. The tirst and most important` ancillary feature is that already described. ot' listening in from the central station by the radio operator over the subscribers telephone line or `other wired circuit, so as to be able to properly adjust and tune the ecntral otlice instrument to the subscribei`s standard wave length.

I claim:

1. A broadcasting system comprising primary high power stations using different' wave lengths, secondary stations havingr ieceiv'ing radio sets tunable to the ditt'erent primary wave lengths and also having relay transmitting apparatus controlledby the receiving set-s and operating on a standard lixed wave length the same for all secondary transmitters, and subscribers receiving radii-b .stations grouped around each secondary transmittingr station in its local area and tuned permanently to the fixed transmitting wave lengths thereof,- thc receiving radio sets at the secondary or relay stations e'aeh comprisingr a tuned circuit. for receiving the primary modulated waves, and a. local oscil- 5v lator circuit tunable to furnish heterodyning waves such that modulated beat waves will always be produced and fed into the transmitting circuit at the standard local trequency.

2. A radio system ol-intercommunication having a plurality of standardized uniform receiving stations divided into groups, all said stations being tuned to one common frequency and ot' sensitiveness limited to the arcas, covered by their respective groups, a local transmitting station for each group working on saidl common wave length, and means for modulating the waves'raated from said transmitting stations as determined by primary7 stations using variable wave lengths, said means comprising a primary circuit tunable to the wave lengths of the primary stations, and a local oseillator circuit tunable to furnish heterodyaing waves therefor, so as to always maintain the beat wave inthe transmitting circuit at thc common or standard wave length for the local group.

3. A broadcasting system comprising a primary station, a secondary distributing station, and a plurality of local receiving stations related to the secondary station and all in permanent tune therewith, mean:` at .said secondary station to receive broadcast waves trom the primary .station at its wart` length, and to .relay and redistribute thc same in its own area at the standard wave length to which its receiving stations are tuned, and means also at said secondary station to determine when its transmitter is actually tuned to the tixed wave length ot' its receiving stations. said relaying mean-l including a local oscillator tunable to furnish waves at heterodyning frequencies for the modulated waves received from the primary station or stations, with a constant beat fre quency giving t'lic standard wave length for local transmission.

Inv tezi'in-iony whereof I hereunto aflix my signature.

' EDWARD E. CLEMENT. 

